Process for the magnetic sizing and grading oe ore



W. G. SWART, F. A. JORDAN, E. W. DAVIS AND T. B. COUNSELMAN. PROCESS FOR THE MAGNETIC SIZING AND GRADING 0F ORE.

1,339,300, Patented May 4,1920.

' EETSSHEET I.

APPLICATION FILED SEPT. 11, I9II.

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W. G. SWART, F. A. JORDAN, E. W. DAVIS AND T. B. COUNSELMAN.

PROCESS FOR THE MAGNETIC SIZING AND GRADING OF ORE.

APPLICATION FILED SEPT. I I, 1917.

1,339,300. atented May 4, 1920.

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W. G. SWART, F. A. JORDAN, E. W. DAVIS AND T. B. COUNSELMAN.

PROCESS FOR THE MAGNETIC SIZING AND GRADING 0F ORE.

APPLICATION FILED SEPT. II, L9H.

1,339,300. PatentedMay 4, 1920.

4 SHEETS-SHEET 3.

W. G. SWART, F. A. JORDAN, E. W. DAVIS AND T. B. COUNSELMAN. PROCESS FOR THE MAGNETIC SIZING AND GRADINGOF ORE.

APPLICATION FILED SEPT. 11. 1.917.

1,339,300. Patented 1134,1920

4 SHEETS-SHEET 4.

UNITED STATES PATENT OFFICE.

WALTER G. SWAR'I, rnnn A. JORDAN, EDWARD w. DAVIS, Ann 'rnnononn B.

counsnmvrnn, or nULurr 'MnvnnsorA.

PROCESS FOR THE MAGNETIC SIZING AND GRADING OF ORE.

Application filed September 11, 1917.

ing of ore, and has for its object to provide a process of that nature by which we may substantially dispense with the use of belt and bucket elevators and similar devices,

and also with the use of screens. In present day processes for magnetic separation and concentration of ores bucket elevators are generally used, and also sizing and grading screens, both of which elements are subject to great wear and require frequent replacing, resulting in the shutting down of the mills, considerable expense incident to such shutting down, and the replacement of the worn out apparatus. By the employment of our process we are enabled to dispense very generally with such elevators and screens, and more efficiently and economically to concentrate and size the ore by the use of magnetic cobbcrs and other apparatus, as.

will be more fully hereinafter explained,

and by the use of the apparatusshown in the ace-1nnpanying drawings, in which- Figure is a perspective view of one cob- 2 is a side elevation of the same.

3 is a diagrammatic view of a wiring arrangement to permit variation of the intensity of the magnets of one cobber,--the first three views being more or less diagram- Fig. 6 isa similar view of-still'another arrangement.

Like numerals refer to 3 like elements throughout the drawings.

Hitherto separation of magnetically susceptiblc ore has been effected by the use of magnetic cobbcrs in the separation and 0011-.

Specification of Letters Patent.

Patented May 4, 1920.

Serial No. 190,718.

centration of iron ore, such as magnetite, which is susceptible of such magnetic separation, but to the best of our knowledge such separation has been crude, and cobbers have never been used for grading both as to size and magnetic susceptibility simultaneously,

as in the case with our process. and apparatus.

In the present day and prior processes the magnetic separation has been purely a separation with regard to the iron or other magnetically susceptible ore content, regardless of size, the limit of effect of such processes being to cause only such a separation, and in no way to effect a grading as to the size of particles of low grade, or such as would be classed as tailings. By our process we are enabled to use as a by-product the tail ing particles where'the same are sized, there being a demand for two sizes especially, one

comparatively large and usable as railroad ballast, and the other of lesser size and usable and in demand as road material. The carrying out of our process enables us to cfi'ect the sizing of these tailing particles so that they areready for immediate use without further crushing or'sizing.

In Fig. 1 is shown a perspective view of one cobber set, this view,as is the case with Figs. 2 and 3, being partially diagrammatic in character. In this view 10 designates a pulley or drum rotating with a shaft 11. 12 designates a driving belt operating to drive the" belt pulley 13 carried upon the hollow sleeve or shaft 14, which is rigidly attached to the cobber drum 15, and which rotates upon the hollow fixed shaft 16. A belt 17, preferably of resilient material, such as rubher or the like, passes around the cobher drum 15 and the drum 10, and terminating adjacent the upper face thereof is a chute 18, intended to supply crushed ore to the surface of the belt 17 and thence thereon to the cobber'drum 15, as will be more fully described hereinafter. Located beneath the cobber drum 15. are the partitions A and B, providing the collection or deposit places X, Y,'and Z'-'see Fig. 2, for'exampleleading to suitable bins, conveyers, or the like,

as maybe desired. Located within the cob ber drum 15 are the magnets 20, illustrated diagrammatically in Fig. 2 and shown more in detail in Fig. 3, where a stationary magnet yoke 20 is provided, from which pro ject outwardly or radially the magnets 20 having pole faces 20 at their outer ends adjacent the inner periphery of the drum 15. In the diagram shown in Fig. 3 a common feed wire 21 is electrically connected to each of the magnet coils, the other terminals of the latter leading to suitable rheostat or current-regulating devices 22 which are in communication with a second feed wire 22*, the purpose of this construction being to enable us to regulate the magnetic intensity of each magnet, as will be obvious, by vaging the current flow in the embodiment own.

In the construction and arrangement of apparatus shown it is to be noted that the first of the magnets in the direction of the belt travel is located adjacent the first contact of the belt with the drum or pulley, for a purpose to be hereinafter described. In the operation of a single unit, such as shown in Figs. 1 to 3, which is typical of our apparatus, crushed ore is fed along the chute 18 upon the surface of the belt 17, upon which it travels toward the cobber drum 15. Each particle of crushed ore as it reaches the cobber drumassuming the magnets to be electrically excited-is subject to a number of forces, the most important of which are momentum due to the inertia of the particles and the velocity of the belt, gravity, and magnetic attraction. The force of gravity, of course, is constant, and, assuming the magnets to be unexcited, each particle will be projected outwardly from the cobber drum in a substantially parabolic path if the resistance of the air is disregarded, the distance of outward projection in the case of any particle varying according to the speed of the belt. With the magnets excited, however, and at a given belt speed, the path traveled by the particles will depend upon the magnetic attraction exerted upon the particles by the magnets. Relatively large particles, not magnetically susceptible, will not be affected by the magnetic attraction, and but inappreciably affected by the resistance of the air, and will closely approximate in their path or trajectory a parabola, and will be projected farthest from the cobber. Small particles of high magnetic susceptibility will be carried around the drum until free from magnetic attraction, then will drop, for example, in the space or bin Z. In between these two extremes are a number of other particles of varying size and magnetic susceptibility, which will be affected differently. For example, finely ground particles or dust, known as fines in the art, will be affected by the resistance of the air, or will be caged or held on the drum by the attracted ore particles until the greater part will either fall in space Y with what are known as the middlings, or

in space Z with the concentrates, even though the magnetic susceptibility be low. Large particles of fairly high grade will be affected more strongly by the centrifugal force of the cobber or velocity of the belt than small high grade particles, and, owing to their relatively lower degree of attraction, due to the greater distances of their centers of magnetic attraction from the magnets, may be projected with the middlings in the space Y. This will also be true of small comparatively low grade particles, which are truly middlings.

By proper regulation of the magnetic attraction exerted on the different particlesthrough rheostat regulation, as shown in Fig. 3, or in a number of other ways, such as by providing different sized magnets, greater current supply, or the likethe separation into three grades may be so effected that all particles falling into space X will be of large size and of practically no magnetic susceptibility, and may be considered as tailings; and in space Z are deposited vcry small particles of high grade mixed with some attached dust particles of low grade, and sometimes larger high grade particles, whose collection with small high grade particles is not deleterious to the carrying out of the process. In space Y will be deposited substantially all particles not to be classified with the large tailings or the high grade concentrate, and which it is desirable in many instances to re-treat and re-crush. Particles in X, if so desired, may be subjected to a further treatment by crushing and separation, but enerally it will be found desirable to consi er them solely as tailings and worthless except for railroad ballast purposes, or the like. The particles falling in space Z will be of high grade and finely comminuted or pulverized, and will require no further preliminary crushing and be of such size as to be taken directly to the ball mill for final grinding preliminary to the final concentration. The particles deposited in space Y will be either subjected to a second separation or conveyed to crushing rolls, which will further crush them to a smaller mesh, after which the operation may be repeated, either to effect a three-class separation as just described, or a two-class separation, as found desirable, in which latter event they are magnetically separated into small high grade particles suitable for the ball mill and large particles of all grades which need re-treatment by crushing, etc.

In some instances after the initial sizing and grading we find it advisable and advantageous to effect a two or three-part separationfor example by means of apparatus diagrammatically illustrated in Fig. 5by which a group of particles which would fall in the space Y, for example, in the illustration in Fig. 2, are subjected to sizing and grading to cast out the larger tailing particles which in the first separation were considered smaller tailings, and which, owing to their lesser distance of travel when projected from the drum, fell into space resulting in the rejection of: the smaller tailings and enabling us to collect the latter without further treatment and deliver them for use in road building. By this first and second stage treatment We are enabled to obtain two sizes of tailings as a by-product without screening or sorting prior to their delivery and sale.

By effecting a three-class separation in the manner described above, it will be apparent that subsequent grinding of the large low grade tailing particles falling in eompart ment X is dispensed with, thereby increasing the elliciency of the apparatus, and de creasing wear on the same. Also, further preliminary handling or crushing of the fine concentrates deposited in space Z is die pense l with, thereby further enhancing the eihciency and economy of the apparatus, these fine concentrates, as stated, being suitable for final treatment in the ball mill. and concentrator. This leaves only the particles deposited in the middling space Y for sub- .equent preliminary treatment, as we term it.

In F l we have illustrated, by means of a flow sheet diagram, a multi-stage process, in. which the rough ore is conveyed by a belt 5, or the like, to the slide 6 which deli rers the same to the crushing rolls 7, which perform the preliminary crushing to desired size of mesh, such as 2 inch, for example, the crushed ore falling upon the chute 18. This chute deposits the ore upon the conveyer belt 30, which travels around the drum 50 and the magnetic drum 30 similar to drum 15, for example, described previously, and a two-part separation is effected thereat, such seuaratiou being ellected with the aid 0? the shed 31, which will divide the ore into large particles for rel-treatment, and comparatively fine (01]."Clltl'fll0l5 which will be carried down the chute 31 to the ball mill. conveyer, or the like, not shown. Particles for re-trcatment are deposited upon the belt 1'? of the next (robber set, the same being similar in general construction to the apparatus shown in Fig. '1 save that it is utilized to perform a two-part separation, whereby large tailing particles. such as were deposited in space X in the apparatus shown in Fig. 1, are carried by the shed 32 to the tailings chute 32. All particles other than the large tailing particles are deposited by the shed 32 upon a second pair of crushing rolls 33, which perform a second crushing operation, reducing the particles to a second size For further retreatmcnt. Such particles after crushing drop upon the belt 34- to be carried around the cobber drum 34", when they are again separated as in the previous stage, and the retained particles subjected to a third crushing by rolls 35, and so on through a fourth crushing and separating stage, after which final preliminary concentration is effected, the last high grade concentrates being taken oil at 38 and the final separation effected by cobber 39, the tailings being conveyed away at lO, and the finally retained material taken away at 41.

It will be obvious that as many stages as are found necessary or desirable may be provided according to the nature of the ore to be treated, but it will be apparent that in any case each stage results in the separation out of the main body of material of one or more portions thereof which need not be retreated, thereby decreasing the amount oi? power, the cost of operation, etc., with each stage. A number of the larger particles in each stage may contain metal in pockets 0r spots, rather then evenly distributed, and each crushing, breaking down these particles and decreasing their size, renders the concentration of the higher grade particles more easy, as the tailing particles or gangue are broken up and away from the metalliferous particles. Each crushing also results not only in the formation of particles small enough to pass a sizing mesh, or the like, but in the formation of dust and very small particles, which need not be recrushed and are suitable for conveyance to the final grinding mill.

In Fig. 5 is shown another form of arrangement in flow sheet form, varying from that shown in Fig. 4 in that the cobber 30 effects a three-class sizing or separation such as was described in connection with the apparatus shown in Fig. 1, the fine concentrates being taken off at 50, the middlings being carried by chute 51 to crushing rolls 33, and the tailings deposited by the shed 52 upon the second cohber belt 17 for resizing, which will result in the tailings or gangue being alren oil at 53, these being of substantially large size, and those worthy of further treatment being carried with the middlings to the rolls In this operation the drum 15, around which the belt 1.? travels, will preferably be maintained with substantially high magnetic excitation, in order to act successfully upon the large particles which it is sizing, since, as will be obvious, the large particles of spotty ore will be attracted in proportion to the square of the distances of their centers of magnetic attraction from the magnet poles, and will require greater magnetic attraction for sizing than small finely ground particles of high magnetic susceptibility, which, by virtue of their smallness, are nearer the magnet poles. The subsequent stages of sizing in the form oi apparatus shown in Fig. 5 are similar to that just described, and terminate with a final separation as in the form shown in F i 4.

In ig. 6 is shown a similar form of apparatus, in which the first cobber 30 of each set effects a three-class separation, as in the apparatus of Figs. 1 and 5, the tailings of large size being taken off at 60, the middlings carried to the crushing rolls 33, and the fines or high grade concentrate being taken off at 61, this process being repeated until the final sizing or separation.

In carrying out our process, particles of iron, steel, and the like, such as broken tools, implements, etc., which cannot be magnetically removed in the treatment of magnetic ores, are easily taken care of in such way as to prevent damaging of the crushing rolls, as is frequently found in present day practice. The ore, as it is conveyed to the first crushing roll, is hand picked for the removal of lar e particles of tool steel, or the like, resulting from broken drills, picks, etc., which large particles are readily removable and visible during the conve ance of the ore to the first crushing rolls. mall particles will readily pass between such rolls, and upon the first magnetic sizing operation, owing to their complete iron constituency they will be carried by the cobber belt to the concentrate collection place, and

' can then be conveyed with such concentrates directly to the ball mill, where, instead of causing damage, they assist in the final grinding or pulverizing of the concentrates.

We are aware, as stated in the preamble, that it has been customar to utilize magnetic cobbers heretofore or crude concentration or separation, but so far as we know we are the first to utilize apparatus of this character for classification which effects not only a grading as to mineral content, but simultaneously a sizing; and we are also the first to carry out such a process, the importance of which will be obvious to those skilled in the art. Also, as stated in effect above, each separation stage of our process results in the removal of the large tailing particles as well as the fine high grade particles, the former of which would ordinarily have to be crushed and recrushed, as well as screened. The crushing of this rejected material is therefore eliminated, as is further preliminary handling of the dust and high grade fines. As stated also the use of screens and bucket elevators is eliminated, resulting in great economy of cost and labor.

It will be obvious that the apparatus for carrying out our process may be varied in numerous ways, and modified, without departing from the spirit of the invention; and we do not therefore wish to be restricted to the process hereinbefore described, except as defined in the appended claims.

What we claim is:

1. A process of sizing and gradin ore consisting in imparting a desired ve ocity to a body of ore particles, then subjecting said particles to a magnetic attraction to withdraw substantially all save large tailing particles from said ore body, then subjecting the remainder of said ore particles to magnetic attraction of such stren h as to withdraw the fine concentrates rom the middling and lar e high-grade particles.

2. A process 0 sizing and grading ore consisting in imparting a desired velocity to a body of ore particles, then subjecting said particles to a magnetic attraction to withdraw substantially all save large tailing particles from said ore body, then subjecting the remainder of said ore particles to magnetic attraction of such strength as to withdraw the fine concentrates from the middling and large high-grade particles and lastly submitting said concentrates to a final magnetic attraction to complete said lastnamed separation.

3. The process of sizing and grading ore consisting in imparting velocity to a body of ore particles in a substantially horizontal direction then subjecting said particles of ore to a magnetic attraction whereby the large tailing particles will be permitted to travel in a substantially parabolic path while the remainder of said particles will be separated therefrom, then subjecting such remainder to a magnetic attraction at such strength as to release the middling and large high-grade particles while withdrawing the fine concentrates therefrom.

4. The process of sizing and grading ore consisting in imparting velocity to a body of ore particles in a substantially horizontal direction then subjecting said particles of ore to a magnetic attraction whereby the large tailing particles will be permitted to travel in a substantially parabolic path while the remainder of said particles will be separated therefrom, then subjecting such remainder to a magnetic attraction at such strength as to release the middling and large high-grade particles while withdrawing the fine concentrates therefrom, and finally continuing last separation by subjecting said concentrates to a further magnetic attraction.

5. A process of sizing and grading ore consisting in imparting velocity to a body of ore particles then subjecting said particles to a magnetic attraction to withdraw all save the large tailing particles then subjecting said withdrawn particles to a relatively weak magnetic attraction to dis-associate the middling and large high-grade particles from the fine concentrates.

6. A process of sizing and grading ore consisting in imparting velocity to a body of ore particles tlien suloj ecting said particles In testimony whereof, WGhLVG subscribed 10 to a magnetic attractlon to wlthdraw all our names.

save the large tailing particles then subject- /VALTER Gr. SW'ART.

ing said Withdrawn particles to a relatively FRED A. JORDAN.

weak magnetic attraction to dis-associate EDWARD W. DAVIS.

the middling and large high-grade particles THEODORE B. COUNSELMAN. from the fine concentrates, then subjecting Witnesses:

such fine concentrates to a relatively strong LYDIA M. VVOODBRIDGE,

attraction to continue said last separation. H. N. MAOHAIG. 

